U.S. Pat. No. 6,770,866 describes a direct pattern writer for creating a pattern of exposed areas on the raster lines in a photosensitive surface of a substrate, by directing a laser beam at a successive spot positions on a photosensitive surface of a substrate, scanning the spot position along raster lines and modulating the beam intensity according to the pattern. This form of writing can be used for example as a replacement for exposure through a photolithographic mask during a semi-conductor manufacturing process. However, for patterns of more than minimal complexity, the time needed to write a pattern in this way is considerably larger than needed for exposure through a photolithographic mask.
U.S. Pat. No. 6,833,234 describes a stereolithographic manufacturing technique, wherein patterns are defined in successive layers. This document proposes to write a pattern with a laser beam using a vector scan of the spot position. The document proposes to trace the contour of an exposed area with a small laser spot size and to use increasingly larger spot sizes to trace successive quasi contours at a distance to the real contour within the exposed area. Thus, the exposure time needed to realize a pattern can be reduced without sacrificing contour resolution. However, vector scanning requires a variable control scanning, which allows for mechanically difficult movements. This limits the achievable scanning speed.